Magnetic bearings of the above mentioned type are used in many applications, e.g. at disk storages for computers and in domestic machines. Bearings of this type are used in these applications to achieve silent operation, extended operation life, and high rotational accuracy. An important advantage of such bearings is that lubricant leakage is prevented because the magnetic field generated by the magnetic bearing sleeve retains the lubricant, which contains mangetizable particle material.
In DE-A-3.304.623 is shown a magnetic bearing incorporating a magnetic bearing sleeve, which on its surface facing the shaft has grooves for causing a hydrodynamic pressure in the magnetic fluid. This device has a complex design, and the shape of the grooves furthermore requires that the shaft be continuously rotated in the same direction.